In 1921, Congress passed the Smith Act, which prohibited the advocacy of overthrowing the U.S. government. In 1951, 14 members of the Communist party in California were convicted under the act. On appeal, the Supreme Court reversed their convictions in what is considered an important expansion of the First Amendment protection of free speech. In Yates, the Court held that the mere advocacy of the overthrow of the government was insufficient for a conviction under the Smith Act, and that more "concrete action" would be necessary before a person could be convicted.